The proposed work deals with the molecular organization of the neuromuscular junction. The major aim of our project is to study the localization and quantification of acetylcholine receptors (AChR) and esterases (AChE) at vertebrate neuromuscular junctions using EM autoradiography as the major tool. The information is then correlated with physiological data obtained by intracellular recording to derive a model of neuromuscular function. Additional studies of these molecules involve their embryonic development, the control of their turnover, and the variants seen in diseases such as muscular dystrophy.